1. Field of the Invention
The present invention relates to a projection display device such as a projection television, and more particularly to an apparatus for fixing an optical system for use in a projection display device which can absorb vibrations from a cabinet which secures and supports the optical system, the vibrations being caused, for example, by an increase in the audio output of speakers associated with the projection display device, thereby preventing the optical system from vibrating or shaking, and ultimately preventing the images and/or pictures generated by the optical system from vibrating or shaking. The present application is based on Korean Patent Application No. 2001-79996, filed Dec. 17, 2001, which is incorporated herein by reference.
2. Description of the Related Art
A projection display device such as a projection television is an apparatus of a type which generates an image or a picture through liquid crystal display (LCD) elements and the like, and then magnifies and projects or images the image or picture on a large-sized screen through a projection lens. Because the large picture of the projection television is satisfying to the consumer, the demand for projection televisions is increasing.
As schematically shown in FIG. 1, a general projection television comprises an optical system 30 disposed on a cabinet 20 in a lower part of casing 10 to selectively transmit light beams generated from a light source through LCD elements, thereby to generate an image and to magnify and project it through a projection lens, a reflecting mirror 40 mounted slantingly at a given angle on an upper part of the rear side of the casing 10 to reflect the image magnified through the optical system 30 toward the front, and a screen 50 disposed at an upper part of the front side of the casing 10 facing the outside of the television so as to transmit or image the image reflected from the reflecting mirror 40.
Due to the critical nature of the operation of the optical system 30 for forming and magnifying an image in the projection television, even a small change in the position of the optical system 30 can have a large effect on the picture which is formed on the screen 50. Accordingly, to prevent the position of the optical system 30 from changing when the projection television is transported or moved, the optical system 30 is fixed to the cabinet 20 forming the casing 10 by means of an apparatus 60 for fixing the optical system 30.
As shown in FIG. 1, the apparatus 60 for fixing the optical system 30 comprises a bracket 62 for supporting and mounting the optical system 30 having a hanger 64 horizontally protruding from a lower part of one side thereof and a fixed end 66 protruding downwardly from the other side thereof, a hanger-receiving groove 22 formed at a portion of the cabinet 20 opposite to the hanger 64 of the bracket 62 to receive it, and screws 68 for fixing the fixed end 66 of the bracket 62 to a portion of the cabinet 20 opposite thereto. On the bracket 62, the optical system 30 is fixed by means of screws and the like. Generally, the optical system 30 is composed of a main projecting part 32 having a lamp, cathode ray tube mirrors for respectively reflecting red, green and blue beams constituting three primary colors from light emitted from the lamp, a LCD panel for forming a desired image by combining the beams reflected from the respective cathode ray tube mirrors, and a projecting lens for magnifying the image formed on the LCD panel, a circuit substrate part 34 for controlling the components such as the lamp, the LCD panel and the like of the main projecting part 32, and a power supplying part 36, such as a transformer, for supplying electric power to the circuit substrate part 34.
Thus, in the conventional apparatus 60 for fixing the optical system 30, the bracket on which the optical system 30 is mounted is fixed to the cabinet 20 by first inserting the hanger 64 into the hanger-receiving groove 22 and then screwing the fixed end 66 thereto, so that the optical system 30 is fixedly maintained in position, particularly in transporting or moving of the projection television.
However, in the projection television, since speakers 70 are installed on the cabinet 20, the conventional apparatus 60 for fixing the optical system 30 presents a phenomenon that the cabinet 20 together with the bracket 62 fixed thereon is trembled by vibrations of the speakers 70.
When the bracket 62 is vibrated by the vibrations of the speakers 70, the optical system 30 for forming the image and projecting it is in turn vibrated, thereby resulting in a vibration of the picture which is reflected through the reflecting mirror 40 from the optical system 30 to be imaged on or transmitted through the screen 50. Therefore, the ultimate picture of the projection television is vibrated. As a result, if the user controls the volume of sound produced by the speakers to be at a high level, the performance of the projection television deteriorates.
Therefore, it is an object of the present invention to provide an improved apparatus for fixing an optical system for use in a projection display device having a large picture and high tone quality, which can not only prevent the position of the optical system from varying during transporting or moving of the projection display device, but can also prevent the picture form vibrating or shaking as a result of a change or difference in the volume of sound produced by the speakers in the projection display device.
This and other objects are provided, according to the present invention, by an apparatus for fixing an optical system for use in a projection display device having a cabinet forming a casing, and an optical system disposed on the cabinet for forming an image and magnifying and projecting the image, comprising a bracket for mounting the optical system; a first vibration-absorbing connector having at least one projection formed at one among one side portion of the bracket and a first counter-portion of the cabinet opposite to the one side portion of the bracket, at least one projection-receiving part for receiving the projection formed at the other among the one side portion of the bracket and the first counter-portion of the cabinet, and at least one first vibration-absorbing member for absorbing vibrations from the cabinet disposed between the projection and the projection-receiving part; and a second vibration-absorbing connector for fixing the other side portion of the bracket to a second counter-portion of the cabinet opposite to the other side portion of the bracket, having a second vibration-absorbing member for absorbing the vibrations from the cabinet interposed between the other side portion of the bracket and the second counter-portion of the cabinet. Also, the second vibration-absorbing connector further includes an intermediate fixing member having a portion directly fixed to the second counter-portion of the cabinet by means of a fixing part, and another portion disposed to be in contact with the second vibration-absorbing member so as to press it against the other side portion of the bracket. Alternatively, the first vibration-absorbing connector can further include at least one elastic supporting member for preventing a direct contact between the one side portion of the bracket and the first counter-portion of the cabinet from being formed.
In a preferred embodiment, the first vibration-absorbing member is formed of a rubber tube formed to wrap the projection and having one end formed in the form of a hemisphere, and the second vibration-absorbing member is formed of a rubber plate attached to the other side portion of the bracket in a contact portion between the bracket and the intermediate fixing member. Also, it is preferable that the fixing part is formed of screws or rivets.
The intermediate fixing member is formed of a plate having at least two fixing protrusions for pressing and unmovably fixing the second vibration-absorbing member attached to the other side portion of the bracket, thereby to ensure that the position of the bracket does not vary when the intermediate fixing member presses the second vibration-absorbing member against the other side portion of the bracket.
Also, the intermediate fixing member has a datum part for guiding an assembling position. The datum part includes at least one datum projection formed on a portion of the intermediate fixing member being in contact with the other side portion of the bracket, and at least one datum projection-receiving part formed in a portion of the other side portion of the bracket opposite to the datum projection to receive the datum projection.